Identification of novel L1CAM mutations using fluorescence-assisted mismatch analysis

✍ Scribed by Pascale Saugier-Veber; Cosette Martin; Nathalie Le Meur; Stanislas Lyonnet; Arnold Munnich; Albert David; Alain Hénocq; Delphine Héron; Philippe Jonveaux; Sylvie Odent; Sylvie Manouvrier; Anne Moncla; Nicole Morichon; Nicole Philip; Daniel Satge; Mario Tosi; T Frébourg

• Book ID: 101260313
• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 314 KB
• Volume: 12
• Category: Article
• ISSN: 1059-7794
• DOI: 10.1002/(sici)1098-1004(1998)12:4<259::aid-humu7>3.0.co;2-a

✦ Synopsis

The L1CAM gene, which is located in Xq28 and codes for a neuronal cell adhesion molecule, is involved in three distinct conditions: HSAS (hydrocephalus-stenosis of the aqueduct of Sylvius), MASA (mental retardation, aphasia, shuffling gait, adductus thumbs), and SPG1 (spastic paraplegia). Molecular analysis of the L1CAM gene is labor-intensive because of the size of the coding region, which is fragmented in numerous exons, and because of the great allelic heterogeneity and distribution of the mutations. The FAMA (fluorescent assisted mismatch analysis) method combines the excellent sensitivity of the chemical cleavage method for scanning PCR fragments larger than 1 kb and the power of automated DNA sequencers. In order to optimize this method for L1CAM, we divided the gene into nine genomic fragments, each including three to four exons. These fragments were PCR-amplified using nine sets of primers containing additional rare universal sequences. A second-stage PCR, performed with the two dye-labeled universal primers, allowed us to generate 1-kb-labeled fragments, which were then submitted to the chemical clivage analysis. Among 12 French families with HSAS and/or MASA, we identified nine distinct L1CAM mutations, seven of which were novel, and an intronic variation. This study demonstrates that FAMA allows rapid and reliable detection of mutations in the L1CAM gene and thus represents one of the most appropriate methods to provide diagnosis for accurate genetic counseling in families with HSAS, MASA, or SPG1.